Articles or materials are often employed in applications where a substantial amount of water is encountered, wherein the water is deleterious in the application because the article or material absorbs the water and swells. For example, particleboard is known by those of skill to be highly water absorptive, swelling to a large degree and sometimes becoming permanently deformed even upon subsequent drying; yet particleboard is often employed underneath formica countertops for kitchens, in items of furniture, or underneath carpeting due to its low cost. Encroachment of water, typically by accidental spills of water or aqueous liquids, causes countertops to bulge noticeably after a spill happens near a seam in the countertop; causes a noticeable permanent bump or lump after a spill happens over a carpeted area; or causes a permanent deformation, bump, mark, or all of these in an item of furniture where a spill contacts the particleboard feature such as a laminated particleboard surface or even an exposed particleboard surface (e.g. the back of a bookcase). Treatments to make particleboard water resistant or waterproof are available, however such treatments add considerable cost to the product, nullifying the cost advantages of using the particleboard in the first place. Polyurethane or epoxy coatings, for example, can be used. An inexpensive method of imparting substantially increased water resistance to particleboard would be highly desirable in the industry.
Increasingly, compostable, biodegradable, and/or edible articles are produced as environmentally sound replacement articles for what traditionally was the purview of petroleum-based plastics. For example, biodegradable disposable comestible containers, utensils, and the like are increasingly being adopted for use in fast food or cafeteria type applications or for home use. Such containers, utensils, and the like are often formed with the inclusion of biopolymers such as starches, cellulose, recycled wood fibers or particles, and the like. However, many biologically sourced polymers are water sensitive and absorb a sufficient volume of water, upon exposure thereto, that integrity of the item is lost and utility destroyed. Recognition of this problem has given rise to the use of materials such as starch blended with or grafted to a polymer that is not biodegradable, such as polyethylene or polypropylene, in order to maintain an acceptable degree of water resistance for the envisioned application. Thus, such articles can only claim a percentage of biodegradable or compostable content. An inexpensive method of imparting substantially increased water resistance to such articles that does not include addition of environmentally harmful materials, non-biodegradable materials, or materials that would be harmful for people to ingest would enable the increased percentage of biodegradable or compostable content use in such articles, and perhaps even provide for 100% biodegradable or compostable content in some applications.
Biodegradable or compostable containers for outdoor use are another set of articles that are produced as environmentally responsible replacement articles for what traditionally was the purview of petroleum-based plastics. Sun et al., U.S. Pat. No. 6,337,097 describe a biodegradable and edible feed container for use with livestock feed materials, wherein a mixture of edible fibers derived from e.g. straw, corn husks, sorghum stalks, soybean hulls, or peanut hulls are compressed and heated with a biologically derived adhesive, such as soy flour adhesive. The containers are not water resistant and thus swell when placed in e.g. muddy fields or areas with standing water. An inexpensive method of imparting substantially increased water resistance to such articles that does not include addition of environmentally harmful or non-biodegradable materials or materials that would be harmful for livestock to ingest would increase the scope of utility for such articles in outdoor applications.
Bowden et al., U.S. Patent Appl. Publication No. 2006/0255507, disclose biodegradable containers for holding food products in dry, damp, or wet conditions wherein starch suspensions are mixed with wood fibers or wood flour; wherein a wax, fatty alcohol, or phospholipid in the mixture is added to the mixture and the mixture is heated to form the container.
Pratt et al., U.S. Pat. No. 5,374,474, disclose blending recycled paper fibers with an isocyanate resin and up to 2% of a wax, then heating and compressing the blend to yield a water-resistant board.
Ozersky et al., U.S. Patent Appl. Publication No. 2008/0265222, disclose surface modified cellulose-containing fibers that include wax as a hydrophobizing agent, and paper products formed using the modified fibers used as fillers.
Clark et al., U.S. Pat. No. 7,399,438, disclose a method of producing thin layer lignocellulosic composites by combining lignocellulosic fibers, an organic isocyanate resin, and a wax, and pressing the mixture at elevated temperature and pressure to form a mat that exhibits good moisture resistance.
Hennis et al., U.S. Pat. No. 7,435,369, disclose a method of manufacture of multilayer gypsum board that includes delivering a wax emulsion additive impregnated in a thin sheet of randomly aligned inorganic fibers to encase the core gypsum within facing layers of the multilayer board.
Rivas, U.S. Pat. No. 5,837,371, discloses a process for coating acrylic fibers in which an acrylic yarn is immersed in an aqueous bath containing a polyethylene, a low melting paraffin wax emulsion, and a high melting paraffin wax emulsion; followed by raising the temperature of the bath, to sequentially coat the fibers of the yarn with the polyethylene, the low melting paraffin wax emulsion, and the high melting paraffin wax emulsion respectively.